Several methods have been used by video reproducing devices to display stereoscopic video (three-dimensional video). The most widely used method visualizes stereoscopic video by showing separate images for perception by the right and left eyes and giving the right-eye and left-eye images the same parallax as when a person views an actual three-dimensional object.
In order to display real-life video stereoscopically, video images are captured simultaneously by two cameras separated horizontally by a distance corresponding to the distance between the eyes. The reproducing process is contrived so that the left eye sees only the images taken by the left-eye camera and the right eye sees only the images taken by the right-eye camera, creating a binocular parallax that causes the images to be perceived stereoscopically. The disclosed art includes various methods for providing a separate video image perceptible to each eye, for providing high video resolution, for reducing the quantity of data needed to represent the video images, and so on.
There is an increasing demand for the recording of stereoscopic video on media used for providing video content, typically DVD and BD media. These media allow, in addition to the display of the video, e.g., movie, forming the major part of the content data, the superimposed display of sub-pictures for displaying subtitles and the superimposed display of graphics for displaying options, samples, guidance, and the like responsive to user operations. These additional video data are also significant components by which value can be added to the video constituting the main part, thereby enhancing the content data. Since video has traditionally been monoscopic (two-dimensional video), additional video information such as superimposed sub-pictures and graphics have also been monoscopic, but when they are superimposed, it has been possible to display them so as to provide visually impressive effects by setting appropriate transparency values to express foreground-background relationships.
When the video content is stereoscopic, since the expressive effect is limited if the additional video information is monoscopic, there is a need for ways to make it possible to render sub-pictures, graphics, and other additional video data in the depth direction.
When conventional monoscopic subtitles are superimposed on stereoscopic video, a problem has been that the stereoscopic video, having parallax, is displayed stereoscopically but the subtitles are displayed as if they were located at an infinite distance, or that whereas subtitles are consistently displayed in the foreground of the image in a monoscopic display they are displayed in the background in a stereoscopic display, which seems strange to the user. In response to this problem, art has been disclosed that displays subtitles at appropriate positions by providing the subtitle data with parameters indicating the display position in the depth direction and reshaping the subtitles when they are combined for display on a stereoscopic image (refer to Patent document 1, for example).